(a) Field of the Invention
The present invention relates to a system and method for virtual LAN (VLAN) configuration of an E-PON (Ethernet-Passive Optical Network), and a recording medium with a stored program of the system and method. More specifically, the present invention relates to a system and method for VLAN configuration of an E-PON, and a recording medium with a stored program of the system and method that converts physical ONU (Optical Network Unit) port information to logical OLT (Optical Link Terminal) port information to compose VLAN membership information based on the logical OLT port and to provide VLAN services for the users of an optical subscriber network.
(b) Description of the Related Art
Currently, the most widely used ultrahigh-speed Internet services are ADSL (Asymmetric Digital Subscriber Line) and Cable Modem services. ADSL uses the existing telephone lines with an ADSL modem installed in the user's computer to provide high-speed Internet service with speeds of 2 to 10 Mbps.
Cable Modems use the existing coaxial cable connection for cable TV service with a cable modem installed in the user's PC, so it can provide ultrahigh-speed Internet service to the user who uses the cable TV service.
These ultrahigh-speed Internet services are satisfactory in performance in providing services such as Internet web surfing (HTTP), E-mail, file transfer (FTP), etc. with much higher transmission capacity of 2 to 10 Mbps, compared with the traditional telephone line modem having a speed of 56 Kbps, but they still have the limitation in meeting the users' emerging requirements such as VoIP (Voice over Internet Protocol), VoD (Video on Demand), Internet broadcasting service, etc.
Moreover, the Cable Modem ultrahigh-speed Internet service is disadvantageous in that its bandwidth decreases with a larger number of users, while the ADSL ultrahigh-speed Internet service has its available bandwidth decrease with an increase in the distance between the central telephone exchange and the user network.
In an attempt to solve this problem, there have been suggested FTTH (Fiber To The Home), FTTB (Fiber To The Building), or FTTC (Fiber To The Curb) that uses an optical cable connection to the subscriber in-home network. In addition, many studies have been made on E-PON (Ethernet-Passive Optical Network) for the sake of enhancing the price-to-service ratio.
E-PON is an Ethernet-associated network constructed with passive elements rather than power-consuming active elements in the optical subscriber network so as to enhance the cost advantage.
The IEEE (Institute of Electrical and Electronics Engineers) 802.3ah Ethernet in the first Mile Task Force has been developing the standard for E-PON.
Now, a description will be given as to a VLAN service providing method of E-PON according to prior art.
FIG. 1 is a schematic diagram of the E-PON according to prior art.
As shown in FIG. 1, the E-PON has a point-to-multipoint structure that includes a plurality of ONUs (Optical Network Units) connected to one OLT (Optical Line Terminal) port through a passive element, a splitter.
Data transfer between an OLT and ONUs is done in the units of an Ethernet frame. Downstream signals from an OLT to ONUs transfer data by broadcasting, and upstream signals from ONUs to an OLT enable allocated bandwidths to be shared among the multiple ONUs by the TDMA (Time Division Multiple Access) method.
FIG. 2 is a configuration diagram of a port-based VLAN service applied to on the OLT that is a partial component of FIG. 1 according to the example of prior art.
The port-based VLAN service configuration on the OLT as shown in FIG. 2 generates VLAN groups, and determines members included in the VLAN groups to construct a VLAN membership table.
The subscriber interface device of the OLT determines the VLAN group of an input frame with reference to the generated VLAN membership table, and provides the VLAN service.
Namely, if the VLAN service is not applied, then the broadcasting traffic is transferred to all the ports in the OLT system; otherwise, if the VLAN service is applied, then it is transferred to only the member ports that belong to the same VLAN group.
In this manner, the VLAN service providing method of an E-PON reduces a system load imposed by the broadcasting traffic and supports mobility and security of users.
As in the case of applying the VLAN function to a two-layer switch, the ONUs connected to one OLT port are inevitably allocated to one VLAN group according to the port-based VLAN function applied on the OLT.
There is thus a demand for a function of dividing the users connected to a same ONU into different groups. However, this function is unfortunately impossible to implement in the method of VLAN configuration based on the OLT port.